What happened
On August 24, 2019, an L-13A Blaník glider, registration OK-683 and 39, was performing training maneuvers at Vrchlabí Airport. The flight, involving a student pilot and an instructor, was conducting exercises from the approved training program, specifically practicing recovery from failed landings (simulated bounces).
During the flare phase of the landing, the instructor intentionally manipulated the controls to demonstrate a simulated bounce. While the student pilot initially responded correctly by applying pressure to the control stick and closing the air brakes to prevent a loss of altitude, the student subsequently re-extended the air brakes fully. This action caused the glider to drop from an altitude of approximately 2 meters AGL, resulting in a hard impact on the grass runway 11. The impact caused extensive deformation to the fuselage skin, the landing gear, and its attachment points.
The investigation
The ÚZPLN investigation examined the flight sequence, the technical condition of the aircraft, and the actions of the crew. The investigation established that the aircraft was airworthy and had undergone its annual inspection earlier that year. The investigation also reviewed witness testimony from an experienced pilot who observed the sequence of the air brake manipulation and the subsequent drop from altitude.
Findings
- The student pilot initially reacted appropriately to the simulated situation but then made an error by re-extending the air brakes.
- The instructor failed to take necessary precautions to mitigate the student's potential for an unpredictable reaction during the demonstration.
- The instructor was unable to intervene in time to correct the student's improper control input.
- The primary cause of the accident was the improper manipulation of the air brake control lever during the practice of a simulated failed landing.
- The structural damage to the L-13A Blaník was entirely due to the force of the hard landing.